The field of art to which this invention pertains is surfactants for aqueous dispersions and to water dispersible epoxy resins.
In recent years, great emphasis has been placed in the coatings and plastics industry upon the replacement of organic-based solvents with aqueous-based systems. The reason for this change has been the increasing cost of these solvents and the pollution problems which result from the escape into the atmosphere of organic-containing compounds, such as hydrocarbons.
Epoxide-containing materials have been known for years to possess extremely desirable properties when used in coatings and plastics. Epoxides impart unique strength and chemical resistance properties to coating and plastics formulations. For these reasons, the use of epoxide resins, and more recently, the use of aqueous emulsions or dispersions of epoxide-containing materials has increased. However, because of their extreme reactivity and relatively high molecular weight, it has often been difficult to prepare stable, low viscosity, epoxy resin dispersions which are of relatively high solids.
Accordingly, there has been a search for dispersants which will permit the preparation of small particle sized and low viscosity, yet high solids, epoxide dispersions. One method of preparing dispersions has been to employ epoxide-based surfactants prepared by reacting two moles of a hydroxy terminated polyethylene glycol with one mole of a diepoxide. However, complete reaction of these materials without undue chain extension is difficult.
An additional problem which has impeded the preparation of epoxide dispersions is the difficulty in preparing satisfactory dispersants which are compatible with the epoxide resins.
These and other problems are overcome by preparing the compositions of the instant invention which may be employed to prepare small particle-sized, low viscosity, high solids, stable, epoxide resin dispersions. The compositions of the instant invention are of particular utility because they are prepared without undue chain extension.
In British Pat. No. 1,069,735, a process is disclosed for the production of a surface active reaction product which comprises reacting two moles of a diisocyanate, one mole of a dihydroxy polyether, and two moles of a monophenol. However, there is no disclosure in this patent of the use of these products with a polyepoxide to render it water-dispersible.
U.S. Pat. No. 3,549,543 discloses a combination of materials useful as low foaming, washing and cleansing agents. Included are certain ethylene oxide adduct dimers prepared using an aliphatic or aromatic diisocyanate. However, the specific compounds of the instant invention are not disclosed, nor is it disclosed to use these materials as co-reactive dispersants for polyepoxides.
U.S. Pat. No. 4,079,028 discloses the preparation of certain polyurethane-based materials employing polyhydroxy compounds, such as di- and trihydroxy benzene. The hydroxyl terminated prepolymers prepared in this patent generally are end-capped with either a monoisocyanate or a mono/diisocyanate mixture. This patent does not disclose the use of Bisphenol A materials, nor their use in combination with an aliphatic polyether glycol.
Non-reactive surfactants, useful in preparing stable aqueous dispersions of epoxy resins, are described in my copending application, Ser. No. 403,897, filed July 30, 1982. These non-reactive surfactants are made by reacting n moles of a diphenol with n+1 moles of a diisocyanate and two moles of a long-chain, aliphatic polyether glycol monoether.
U.S. Pat. No. 4,315,044 discloses stable epoxy resin dispersions made from the reaction product of (a) a diglycidyl ether of a dihydric phenol, (b) a dihydric phenol and (c) a diglycidyl ether of a polyoxyalkylene glycol.